Extensible and contractable devices

ABSTRACT

A linearly extensible and contractible device comprising a plunger component slidable in a cylinder component has the plunger urged in one direction in the cylinder by compressed gas, and mechanical locking means operative to hold the plunger against movement in the other direction and normally held engaged by the gas pressure are released by exerting thereon an opposing force sufficient to overcome the gas pressure.

United States Patent [72] inventor Wilfred N. Bainbridge Leamington Spa, England [2]] Appl. No. 796,050 [22] Filed Feb. 3, 1969 [45] Patented Feb. 16, 1971 [73] Assignee Automotive Products Company Llmlted Leamington Spa, Warwickshire, England [54] EXTENSIBLE AND CONTRACT/ABLE DEVICES 6 Claims, 9 Drawing Figs.

[52] US. Cl. 188/67 511 1m. (:1 Fl6d 63/00 [50] Field of Search 92/130, 134,21 (MR), 21, 22, 28, 27, 25,136,l8;74/143, 575, 576,577; 267/64,65, 121, 127; 188/67; 92/20,15, 18, 23

[56] References Cited UNITED STATES PATENTS 1,213,363 l/l917 Henry 92/21X 2,099,368 11/1937 Levy 92/134X 2,118,890 5/1938 Maes... 92/24X 2,664,073 12/1953 Pine r 74/575X 2,771,060 11/1956 Allbright 92/24 3,062,591 11/1962 Brimhall 92/130X 3,135,171 6/1964 Michalek 92/129X 3,160,078 12/1964 Hiemstra et a1.. 92/18X 3,444,830 5/1969 Doetsch 267/64 Primary Examiner-Martin P. Schwadron Assistant Examiner- Leslie J. Payne Attorney- Lawrence J. Winter Patented Feb. .16, 19,71

2 Sheets-Sheet 1 aw Tm) This invention relates to extensible and contractible devices for use as struts or tension members, which are suitable for holding one component of an assembly in any one of a number of different positions relative to another component. An example of the use of such a device is in connection with seats, particularly vehicle seats, the backs-of which are mounted for angular movement between a substantially upright position and a position approaching the horizontal, and can be held in intermediate positions.

The device according to the invention is of the known type comprising a plunger slidable in a cylinder and urged in a direction to extend or contract the device by gas under pressure stored therein.

According to the present invention, a linearly extensible and contractible device for use as a strut or tension member comprises a plunger component slidable in a cylinder component, a chamber in said cylindercomponent to contain compressed gas acting on the plunger component to urge it in one direction relative to the cylinder component, mechanical locking means operative at all relative positions of the plunger and cylinder components to hold the plunger component 7 against movement relative to the cylinder component, means operated by the gas pressure in the chamber to apply an engaging force to the locking means to urge said locking means at all times towards the engaged position and means to release said locking means by exerting thereon an opposing force suf ficient to overcome the engaging force applied thereto by the gas pressure. v

The locking means may comprise one or more pivoted arm members mounted on one of the components of the device and having teeth to the cooperate with a longitudinal array of ratchet teeth on the other component,-and a thrust member subjected to the gas pressure in the device and acting on the arm or arms to bias the teeth thereon into engagement with the ratchet teeth, the releasing means acting to pivot the arm or arms in a direction to disengage the said teeth.

The invention will be hereinafter described with reference to the accompanying drawings, in which:

FIG. 1 is a side elevation of a vehicle seat showing a device according to the invention, mounted thereon to control the inclination of the seat back;

FIG. 2 is an elevation, on a larger scale, of the device showing its connections to the seat;

FIG. 3 is a longitudinal section through the device shown in FIG. 2, but including a modified stroke adjusting means;

FIG. 4 is a plan view of the device;

FIG. 5 is a cross section on the line 5-5 of FIG. 4:

FIG. 6 is a longitudinal elevation, partly in section, corresponding to part of FIG. 2, and showing a modification;

FIG. 7 is a cross section on the line 77 of FIG. 4 showing one form of releasing means for the locking means;

FIG. 8 is a cross section similar to FIG. 7 showing another form of releasing means; and

FIG. 9 is a plan view of the parts shown in FIG. 8.

it is to be understood that whilst the invention is shown in the drawings, and will be described in detail, as applied to a vehicle seat, it is not limited to this use and has many other applications.

Referring to the drawings, and more particularly to FIG. 1 thereof, a vehicle seat having a cushion 10 supported on a frame 11 and a back 12 pivotally mounted at 13 about an axis along the rear edge of the cushion 10 has a lug 14 fixed to the seat frame and an arm 15 depending from the lower edge of the back 12, an extensible and contractible device 16 according to the invention being mounted between the lug 14 and the arm 15 and providing resilient loading tending to urge the seat back towards an upright position. The device 16, which contracts to permit rearward tilting from the upright position is normally held positively against such contraction, but can be allowed to contract to provide such movement at the will of an occupant of the seat.

The device 16, as shown in FIGS. 2, 3 and 4 comprises one component 17 in the form of a cylinder, closed at one end at 18, and having a clevis 19 at the said closed end for pivotal connection to the arm 15. A plunger 20, forming the other component of the device, includes a head 21 fitting closely in the cylinder 17, the head 21 being grooved circumferentially to receive a packing ring 22, and a tubular stem 23 extending outwardly through the other end of the cylinder 17. A tube 24 i mounted on the outer end of the stem 23 by means of a screwthread at 25 is formed on its peripheral surface with ratchet teeth 26 extending around the said tube.

The end of the cylinder 17 remote from the ratchet teeth 34 to cooperate with the ratchet teeth 26 on the tube 24. The annular disc member 29 in the counterboard part of the cylinder has a frustoconical surface 35, the arrangement being such that thrust exerted on the arms 33 by the engagement of the said disc member 29 with the arms urges the ends of the said arms extending towards the closed end of the cylinder 17 radially outwardly and so urges their other ends radially inwardly to bring the teeth 34 thereon into engagement with the ratchet teeth 26 on the tube 24.

In an alternative arrangement, shown in FIG. 6, the disc member 29 is formed integral with two longitudinally extend ing arms, one of which is shown at 30., each arm 30 having, at its end remote from the disc member 29, a cross-piece 30a the ends of which engage with lugs 30b on the arms 33 so as to produce a moment about the pivots of the arms 33 tending to urge the teeth thereon into engagement with the ratchet teeth 34.

Gas, such as nitrogen, under pressure, is stored in the cylinder 17 between the closed end thereof and the plunger head 21, the said gas being conveniently pumped into the cylinder through a valve 36 at the outer end of the plunger stem 23.

A restricted orifice 37 in the plunger head connects the space between the closed end 18 of the cylinder and the said plunger head 21 to the annular space between the plunger head 21 and the nearest disc member 28 in the counterbore 27, and liquid, preferably a lubricating oil, is contained in the annular space between the sealing members 31 supported by the two disc members 28 and 29.

The gas pressure acts on different areas of the plunger 21 on opposite sides thereof the relation of the said areas being such that the gas pressure exerts at all times a thrust tending to urge the plunger outwardly. The said gas pressure also acts, through the liquid between the disc members 28, 29, on the outer one 29 of said disc members, and thus acts on the arms 33 to hold them in engagement with the ratchet teeth 26 on the tube 24. The ratchet teeth 26 are arranged to resist inward movement of the plunger 20 and thus hold the plunger positively against contraction. The total forces resisting movement of the plunger in the extending direction are sufficient to hold it against extension by the gas pressure when the teeth 34 on the arms 33 are in engagement with the ratchet teeth 26. Thus the seat back will normally remain at any inclination to which it is set, but its inclination can be adjusted when the arms 33 are disengaged.

To enable the strut to be contracted or extended, means are provided for urging the pivoted arms; 33 apart. Such means may, for example, as shown in FIG. 7 comprise a liquid pressure motor cylinder device mounted between ears carried by the said arms and connected to a suitable source of liquid under pressure such as a manually operated master cylinder. Alternatively the may be urged apart by a manually operably lever or wedge mechanism, an example of such a mechanism being shown in FIGS. 8 and 9.

Referring to FIG. 7 it will be seen that the 47 on the said arms and extends parallel to the length of the strut. The lever 46 has integral with it a disclike part 48 which lies in arcuatc undercut recesses 49 in the lugs 47. Angular movement of the lever 46 causes it to expand the width of the gap between the lugs, thus moving the arms apart to separate the teeth 34 from the teeth 26.

The arms 33 may be guided to hold them against movement transverse to their normal pivotal motion by bar members 51 integral with the cylinder 17 and providing parallel guide surfaces 52 one on each side of the arms. The said bar members 51 may cooperate with shoulders 53 on the arms 33 to transmit end thrust from the arms to the cylinder.

lnserts 54 of nylon or other plastics material may be provided in the toothed ends of the arms 33 to reduce the noise caused by the teeth on said arms riding over the ratchet teeth 26 on the sleeve 24 when the device is being contracted.

To adjust the stroke of the devices, an adjustable stop is mounted on the outer end of the sleeve 24, the stop comprising a divided ring 55, formed internally with teeth complementary to the ratchet teeth on the tube, the parts of the ring 55 being held together around the tube by a spring wire clip 56 engaging in a circumferential groove around the ring.

As shown in FIG. 2, the plunger component 20 may be attached to the lug 14 on the seat by clamping a clevis member 57, pivoted to the lug 14, against one side of the ring 55 by means ofa sleeve nut 58, the ring 55 being first adjusted to the desired position on the sleeve 24 and the clevis member then being clamped in position by the sleeve nut 58.

Alternatively, as shown in FIG. 3, a clevis member 59 for connection to the lug 14 may have a screw-threaded stem 61 screwed into the tube 24, so that the ring 55 can be moved to adjust the stroke independently of the distance between the pivots of the device.

it will be appreciated that the device according to the invention may be used for many purposes. Since, during all changes of length of the device, gas must pass through the restricted passage 37 in the plunger head, the extension or contraction is subject to damping and, because the stored gas pressure decreases during extension of the device, the force producing extension tends to decrease as the position of the full extension is approached.

it will be understood that, whilst the device has been described in a form such that the gas pressure tends to produce extension, it may be modified in such a way that the gas pressure produces contraction.

lclaim:

l. A linearly extensible and contractible device for use as a strut or tension member and the like, comprising a cylinder with a slidable plunger having a plunger head mounted thereon, a gas chamber disposed on one side of said plunger head, fluid under pressure in said gas chamber continuously urging said plunger toward the other end of said cylinder,

mechanical locking means engaging said plunger to prevent relative movement of it with respect to said cylinder, thrust means mounted on said plunger on the opposite side of said plunger head from said gas chamber engaging said mechanical locking means, restricted passage means in communication with said gas chamber and said thrust means to continuously apply a fluid pressure force against said thrust means to maintain it engaging said locking means, and release means operatively connected to said locking means, and release means operatively connected to said locking means to disengage it from said plunger, said release means being separate from and out of communication with the interior of said cylinder and said gas chamber.

2. A linearly extensible and contractible device according to claim 1 wherein said locking means comprise at least one pivoted arm member mounted on said cylinder and having teeth to cooperate with a longitudinal array of ratchet teeth on said plunger, and said thrust means acts on said arm to bias the teeth thereon into engagement with the ratchet teeth, and said release means acts to pivot said arm in a direction to disengage said teeth.

3. The linearly extensible and contractible device, according to claim 2 wherein the plunger is provided with a stem, the gas chamber is formed between the plunger head and a closed end of the cylinder, the other end of the cylinder is open and has at least one slot in which said pivoted arm member is mounted, and a counterbored portion of the cylinder adjacent its open end has shdably mounted thereon, between the wall ofthe counterbore and the stem, two axially spaced disc members supporting sealing members on their mutually adjacent faces and defining between them a liquid-filled chamber, one of said disc members constituting said thrust means and the other being subjected to the gas pressure in the gas chamber which is transmitted to the counter bore through the restricted passage means in the plunger head.

4. A linearly extensible and contractible device according to claim 3, wherein said release means comprises a liquid pressure motor cylinder acting to urge said pivoted arm member away from said plunger.

5. A linearly extensible and contractible device according to claim 4, wherein said release means comprises a lever operable to urge said pivoted arm member laterally away from said plunger.

6. A linearly extensible and contractible device according to claim 5, wherein a longitudinally adjustable stop member is provided on said plunger. 

1. A linearly extensible and contractible device for use as a strut or tension member and the like, comprising a cylinder with a slidable plunger having a plunger head mounted thereon, a gas chamber disposed on one side of said plunger head, fluid under pressure in said gas chamber continuously urging said plunger toward the other end of said cylinder, mechanical locking means engaging said plunger to prevent relative moVement of it with respect to said cylinder, thrust means mounted on said plunger on the opposite side of said plunger head from said gas chamber engaging said mechanical locking means, restricted passage means in communication with said gas chamber and said thrust means to continuously apply a fluid pressure force against said thrust means to maintain it engaging said locking means, and release means operatively connected to said locking means, and release means operatively connected to said locking means to disengage it from said plunger, said release means being separate from and out of communication with the interior of said cylinder and said gas chamber.
 2. A linearly extensible and contractible device according to claim 1 wherein said locking means comprise at least one pivoted arm member mounted on said cylinder and having teeth to cooperate with a longitudinal array of ratchet teeth on said plunger, and said thrust means acts on said arm to bias the teeth thereon into engagement with the ratchet teeth, and said release means acts to pivot said arm in a direction to disengage said teeth.
 3. The linearly extensible and contractible device, according to claim 2 wherein the plunger is provided with a stem, the gas chamber is formed between the plunger head and a closed end of the cylinder, the other end of the cylinder is open and has at least one slot in which said pivoted arm member is mounted, and a counterbored portion of the cylinder adjacent its open end has slidably mounted thereon, between the wall of the counterbore and the stem, two axially spaced disc members supporting sealing members on their mutually adjacent faces and defining between them a liquid-filled chamber, one of said disc members constituting said thrust means and the other being subjected to the gas pressure in the gas chamber which is transmitted to the counter bore through the restricted passage means in the plunger head.
 4. A linearly extensible and contractible device according to claim 3, wherein said release means comprises a liquid pressure motor cylinder acting to urge said pivoted arm member away from said plunger.
 5. A linearly extensible and contractible device according to claim 4, wherein said release means comprises a lever operable to urge said pivoted arm member laterally away from said plunger.
 6. A linearly extensible and contractible device according to claim 5, wherein a longitudinally adjustable stop member is provided on said plunger. 